Abrasive tools that utilize relatively hard particles are known in the art. These include tools with embedded single crystal diamonds and polycrystalline diamonds (PCD). One technique for manufacturing abrasive tools of this type involves placing the relatively hard particles in a matrix material such as a metal powder or resin, then compressing and sintering the material onto the surface of the tool body. When polycrystalline diamonds are utilized, the final compressed-and-sintered product is often referred to as a polycrystalline diamond compact (PDC) material. U.S. Pat. No. 7,234,550 to Azar relates to a process for manufacturing drill bit inserts. U.S. Pat. No. 4,925,457 to deKok relates to a variant of this manufacturing process wherein a carrier such as a wire mesh helps secure the relatively hard particles to the tool body and also serves to locate the relatively hard particles in a desired pattern. The '550 patent to Azar further relates that relatively high temperatures associated with the sintering process are known to decrease the service life of both natural and synthetic diamonds in such abrasive tools.
A second technique for manufacturing abrasive tools involves electroplating the relatively hard particles to a tool body metal surface. In this technique a relatively thin layer of relatively hard particles is placed onto the metal surface, and successive layers of metal are electroplated onto the substrate and particles until the relatively hard particles are secured. Abrasive tools manufactured by the electroplating technique tend to be delicate in that the relatively hard particles are secured only by relatively thin layers of metal. U.S. Pat. No. 6,745,479 to Dirks relates to a process for manufacturing such abrasive tools wherein diamond particles are secured to a surface via layers of electroplated chromium. Variants of these manufacturing techniques are also known in the art.
Abrasive tools that utilize relatively hard particles are commonly employed as drills, disks, wheels and the like for drilling, deburring, grinding, dressing, polishing, lapping, honing, and roughening. Such abrasive tools typically reach the end of their service life when one of the following occurs: The majority of the relatively hard particles are dislodged and removed from the cutting surface of the tool thereby decreasing the cutting efficiency; or the relatively hard particles on the cutting surface have fractured and made dull thereby decreasing the cutting efficiency. There is a need in the art to provide relatively hard particle-based abrasive tools that are resistant to these degradations and as a result have improved service life. In particular, there is a need in the art to provide improved service life for abrasive tools that utilize single crystal and polycrystalline diamond particles.
Cryogenic thermal cycling is known in the art of materials treatment, and is often used to strengthen and provide increased wear properties of certain articles of manufacture. U.S. Pat. No. 6,332,325 to Monfort relates to an apparatus and method for strengthening certain articles of manufacture through cryogenic thermal cycling. U.S. Pat. No. 6,314,743 to Hutchison relates to a cryogenic tempering process for certain printed circuit-board drill bits. U.S. Pat. No. 6,164,079 to Waldmann relates to cryogenic treatment of certain silicon nitride tool and machine parts. U.S. Pat. No. 5,447,035 to Workman relates to cryogenic treatment of certain types of brake pads. U.S. Pat. No. 7,163,595 to Watson relates to a cryogenic thermal process for treating certain metals to improve structural characteristics. U.S. Pat. No. 7,297,418 also to Watson relates to cryogenic thermal cycling treatment of certain carbide materials commonly used for cutting tools, drills and the like. United States Patent Application 20050047989 to Watson relates to cryogenic treatment of certain diamond materials.
The '989 patent application by Watson relates to a process by which certain diamond and diamond compact materials can purportedly be toughened. Thermal treatment of many materials can produce a material with increased fracture toughness, but at the expense of strength, hardness, and wear properties—the latter of which may be relatively important for abrasive tools. The subject of strength and fracture toughness is thoroughly discussed in the text “Strength and Toughness of Materials” by Toshiro Kobayashi.
Accordingly, there is a need for certain treatments for relatively hard-particle based abrasive tools that provide increased cutting performance through increases in strength, hardness, fracture toughness and wear resistance. In particular, there is a need for cryogenic thermal cycling treatments for diamond-based abrasive tools that provide increased cutting performance and service life through increases in strength, hardness, fracture toughness and wear resistance.